Frequent gene duplications in the genome incessantly supply new genetic materials for functional innovation presumably driven by positive Darwinian selection. This mechanism in the desaturase gene family has been proposed to be important in triggering the pheromonal diversification in insects. With the recent completion of a dozen Drosophila genomes, a genome-wide perspective is possible. In this study, we first identified homologs of desaturase genes in 12 Drosophila species and noted that while gene duplication events are relatively frequent, gene losses are not scarce, especially in the desat1–desat2–desatF clade. By reconciling the gene tree with species phylogeny and the chromosomal synteny of the sequenced Drosophila genomes, at least one gene loss in desat2 and a minimum of six gene gains (resulting in seven desatF homologs, α-η), three gene losses and one relocation in desatF were inferred. Upon branching off the ancestral desat1 lineage, both desat2 and desatF gained novel functions through accelerating protein evolution. The amino acid residues under positive selection located near the catalytic sites and the C-terminal region might be responsible for altered substrate selectivity between closely related species. The association between the expression pattern of desatF-α and the chemical composition of cuticular hydrocarbons implies that the ancestral function of desatF-α is the second desaturation at the four carbons after the first double bond in diene synthesis, and the shift from bisexual to female-specific expression in desatF-α occurred in the ancestral lineage of Drosophila melanogaster subgroup. A relationship between the number of expressed desatF homologs and the diene diversification has also been observed. These results suggest that the molecular diversification of fatty acid desaturases after recurrent gene duplication plays an important role in pheromonal diversity in Drosophila.

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The Oriental Melolontha guttigera species group is revised with synopsis, a key to species, description of a new species, redescriptions of known species, remarks, illustrations, and distribution map, The guttigera species group is the only representative of the genus with its distribution extending southward from the eastern Himalayas to Indochina and crossing the equator to Java. Five species are known in this group, including a new species, M. setifera, from Myanmar. Lectotypes are designated for Melolontha guttigera Sharp and Melolontha weyersi Brenske. A key for the East and South-East Asian species group of the genus is provided, An annotated checklist of Melolontha species recorded in the region is updated in which several nomenclatural changes are proposed as follows: Hoplosternus carinata Brenske, Hoplosternus malaccensis Moser, Hoplosternus incana Motschulsky, and Hoplosternus shanghaiana Brenske are transferred to Melolontha; Melolontha fuliginosa Fairmaire and Melolontha laticauda Bates are transferred to Exolontha; Hoplosternus laevipennis Blanchard is transferred to Tocama; Hoplosternus heydeni Moser n. syn. = Melolontha chinensis (Guérin-Méneville); Melolontha nitidicollis Blanchard n. syn. = Melolontha indica Hope; Hoplosternus bifurcatus Brenske n. syn. = Melolontha furcienanda Ancey; Melolontha albidiventris Fairmaire n. syn. = Tocama rubiginosa (Fairmaire); Hoplesternus squamulatus Frey n. syn. = Tocama laevipennis (Blanchard); Melolontha hualiensis Kobayashi et Chou n. syn. = Melolontha minima Kobayashi.

The six Miridiba Reitter, 1902 species, including Miridiba taoi Li & Wang, new species, Miridiba huesiotoi Li & Yang, new species, and Miridiba taipei Wang & Li, new species from Taiwan are reviewed. A key for the identification of adults is provided. The following information is provided for each species: literature review, synonyms, diagnoses, data of material used, description or redescription, illustrations, distributional data, and remarks.

Three new species of the Oriental bolboceratine genus Bolbochromus Boucomont 1909, Bolbochromus minutus Li and Krikken, sp. n. (Thailand), Bolbochromus nomurai Li and Krikken, sp. n. (Vietnam), and Bolbochromus malayensis Li and Krikken, sp. n. (Malaysia), are described from continental Southeast Asia with diagnoses, distributions, remarks and illustrations. The genus is discussed with emphasis on continental Southeast Asia. A key to species known from Indochina and Malay Penisula is presented. An annotated checklist of Bolbochromus species is presented.